GE 7-7650B TV no vertical sweep

M

Mike

Guest
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke output,
(as i assumed).
 
"Mike" <mbates14@fuse.net> wrote in message
I got this TV from a friend that I could have.
The TV has no vertical sweep.
im suspecting uPC1379C. throwing the service switch does nothing.
any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
------------------------
Click to expand...

Mike:
Before you replace the chip, check for cracked, dry or otherwise faulty
solder connections near and around the area..... also ESR check the
electrolytics in the vertical deflection circuitry and then verify that the
flyback derived B+ getting to the uPC1739 chip? No ESR meter.... then
REPLACE all the electrolytics in that circuit.... no big deal, about a half
dozen or so.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.

If i had the pinout or datasheet to that IC, id be getting somewhere. can
you locate it?



"Sofie" <sofie@olypen.com> wrote in message
news:vp0vmnbskiindd@corp.supernews.com...
"Mike" <mbates14@fuse.net> wrote in message
I got this TV from a friend that I could have.
The TV has no vertical sweep.
im suspecting uPC1379C. throwing the service switch does nothing.
any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
------------------------

Mike:
Before you replace the chip, check for cracked, dry or otherwise faulty
solder connections near and around the area..... also ESR check the
electrolytics in the vertical deflection circuitry and then verify that
the
flyback derived B+ getting to the uPC1739 chip? No ESR meter.... then
REPLACE all the electrolytics in that circuit.... no big deal, about a
half
dozen or so.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Click to expand...
 
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.

If i had the pinout or datasheet to that IC, id be getting somewhere. can
you locate it?




"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.

If i had the pinout or datasheet to that IC, id be getting somewhere. can
you locate it?

"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.

If i had the pinout or datasheet to that IC, I would be getting somewhere.
can
you find the pinout to it.



"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
"Mike" <mbates14@fuse.net> wrote in message
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.
If i had the pinout or datasheet to that IC, I would be getting somewhere.
can you find the pinout to it.
----------------------
Click to expand...

Mike:
Don't worry about the pinouts or waveforms yet..... check the simple stuff
first as outlined in my previous posting to you.... attatched below:

Before you replace the chip, check
for cracked, dry or otherwise faulty
solder connections near and around the
area..... also ESR check the
electrolytics in the vertical deflection
circuitry and then verify that the
flyback derived B+ getting to
the uPC1739 chip? No ESR meter....
...then REPLACE all the electrolytics in t
hat circuit.... no big deal, about a half
dozen or so.
--
Click to expand...
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
snipped:
"Mike" <mbates14@fuse.net> wrote in message
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.
If i had the pinout or datasheet to that IC, I would be getting somewhere.
can you find the pinout to it.
im suspecting uPC1379C. throwing the service switch does nothing.
-----------------------------------------------
Click to expand...

Mike:
I found the pin out for the uPC1379C.... as follows:
Pin #
1 vert sync in
2 vert osc
3 vert osc
4 vert Vcc
5 volt boost out
6 vert feedback
7 volt boost out
8 vert amp out
9 horiz pulse out
10 horiz Vcc
11 vert blank adj
12 horiz osc
13 afc det out
14 horiz afc in
15 sync sig sep in
16 sync sig sep out
tab ground
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------
 
ok, thanks a million!

im going to look into the vertical portion of the chip.

couldnt be the IC itself, because according to this, i wouldnt have horix
either, and i do have horiz and HV.


"Sofie" <sofie@olypen.com> wrote in message
news:vp1efqt869ie46@corp.supernews.com...
snipped:
"Mike" <mbates14@fuse.net> wrote in message
thing is, i was going to check for common waveforms, and volteges. I did
that before on my currently working 32 inch.
If i had the pinout or datasheet to that IC, I would be getting
somewhere.
can you find the pinout to it.
im suspecting uPC1379C. throwing the service switch does nothing.
-----------------------------------------------

Mike:
I found the pin out for the uPC1379C.... as follows:
Pin #
1 vert sync in
2 vert osc
3 vert osc
4 vert Vcc
5 volt boost out
6 vert feedback
7 volt boost out
8 vert amp out
9 horiz pulse out
10 horiz Vcc
11 vert blank adj
12 horiz osc
13 afc det out
14 horiz afc in
15 sync sig sep in
16 sync sig sep out
tab ground
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------
Click to expand...
 
sofie, thanks. that pinout helped me find the problem!


ok, here goes so someone might need this for future reference:

on pin 4, is vertical VCC. well, guess what. nothing. so i traced the source
back to pin 7, and pin 7 provides the B+ to the vert. the B+ on pin 7 is
10V. so that is good.

the pin 7 output goes through a diode, and a cap which is grounded. then
through a 100ohm resistor and another cap thats grounded, and to pin 4.

so, there is 2 caps on each side of the resistor. well, the diode tested
fine, the resistor tested 68ohms, which was way out of tolerence. I bypassed
the resistor and the 2 caps by wiring pin 4 directly to the diode. BOOM.
restored the vertical deflection! when i removed the short, the vertical
remained the same until one of the caps discharged and it dropped back to a
line.

I replaced the resistor, and it still read 68ohms, and still no vertical.

I replaced both caps, and bingo. vertical restored.

those 2 caps, one of them went high in ESR loading the B+ to almost nothing.

thanks for your tips and pinout sofie!



"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
sofie, thanks. that pinout helped me find the problem.


ok, here goes so someone might need this for future reference:

on pin 4, is vertical VCC. well, guess what. nothing. so i traced the source
back to pin 7, and pin 7 provides the B+ to the vert. the B+ on pin 7 is
10V. so that is good.

the pin 7 output goes through a diode, and a cap which is grounded. then
through a 100ohm resistor and another cap thats grounded, and to pin 4.

so, there is 2 caps on each side of the resistor. well, the diode tested
fine, the resistor tested 68ohms, which was way out of tolerence. I bypassed
the resistor and the 2 caps by wiring pin 4 directly to the diode. bingo.
restored the vertical deflection! when i removed the short, the vertical
remained the same until one of the caps discharged and it dropped back to a
line.

I replaced the resistor, and it still read 68ohms, and still no vertical.

I replaced both caps, and bingo. vertical restored.

those 2 caps, one of them went high in ESR loading the B+ to almost nothing.

thanks for your tips and pinout sofie.

"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
uh oh, i have another problem. no color






"Mike" <mbates14@fuse.net> wrote in message
news:gL_jb.75830$uJ2.24734@fe3.columbus.rr.com...
I got this TV from a friend that I could have.

The TV has no vertical sweep.

im suspecting uPC1379C. throwing the service switch does nothing.

any ideas? im not sure the pinouts on this IC, or else I would check for
correct volteges and proper waveforms. There is nothing on the yoke
output,
(as i assumed).
Click to expand...
 
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